Field of the Invention
The present invention relates to a dental adhesive resin composition for imparting firm adhesion to dental nonprecious alloys or dental porcelain materials, thereby enhancing the usefulness thereof, without giving damage to the excellent physical properties of a (meth)acrylic resin materials widely used in dentistry.
Dental alloys have higher thermal conductivity than (meth)acrylic resin materials, and do not only serve to mitigate a feeling of physical disorder upon putting-in of dentures in view of the sense of temperature or taste, but do also excel in mechanical strength, dimensional accuracy and water resistance, as compared with the (meth)acrylic resin materials. Taking such advantages, the dental alloys are used at metal-based dentures or bridges in combination with the (meth)acrylic resin materials, and are considered to be increasingly demanded with the arrival of aging society.
Co-Cr and Ni-Cr base alloys typical of the dental nonprecious alloys have a Young's modulus of about two-fold at a specific gravity of about 1/2, as compared with precious alloys such as gold alloys, gold/silver/palladium alloys and platinum plus gold alloys, and offer considerable advantages to patients, since they do not only excel in the resistance to discoloration, but are also low price. Thus, the amount of the Co--Cr and Ni--Cr base alloys used are increasing year by year.
Commercially available (meth)acrylic resin materials for the preparation of dentures have no chemical bonding force with respect to dental alloys. For that reason, it is required to carry out designs at the time of preparing dentures, taking various mechanical retention forms into consideration, thus making technicians' manipulation complicated. In addition, due to the absence of any chemical bond between the dental alloys and the resin materials, a gap occurs at the junction of the resin and the metal, i.e., the so-called finishing line. This poses a number of problems such as partial separation and breakage of the resin, contamination and discoloration of portions of the resin around that junction due to the accumulation of foodstuff residues and filth, occurrence of denture plaque and odor, etc.
If (meth)acrylic resin materials could chemically bonded to metals, then the aforesaid problems would be solved. In addition, new techniques and denture designs could be introduced in dentistry.
Some attempts have been made so as to achieve such bonding. For instance, according to one of the methods heretofore reported, the surface of a metal is etched with an inorganic acid, applied thereon with a bonding agent, and is further laminated thereon with an MMA base plate resin material. According to another method, 4-methacryloxyethyl trimellitic anhydride is incorporated into an MMA monomer. However, these methods make technicians' manipulation complicated, and give no bonding force with respect to porcelain or ceramic teeth. According to a further method, a silane compound is added to an MMA monomer to afford adhesion to porcelain teeth. However, it is expected that this method would give no bonding force to any metal.
There are still further reports regarding porcelain teeth wherein a silane compound and an unsaturated carboxylic acid are allowed to coexist in an MMA monomer, and adhesive compositions for giving adhesion to metals. However, any high and stable adhesion is not always obtained.